STUDIES ON THE SYNTHESES AND BACTERICIDAL ACTIVITIES OF ACYLAMINOETHYL GLYCINES AND OF THEIR CYCLO-CONDENSATION PRODUCTS

Two series of new compounds:the aliphatic acylaminoethyl glycines (Ⅰ) and their cyclo-condensation products-allphatic acylaminoethyl plperazlnones (Ⅱ) were synthesized.The results of bactericidal and bacteriostatic tests show that the two series of compounds are good bactericldal agents.

Identification,Characterization,and Probiotic Potentials of Lactobacillus pentosus SF-1

In recent years probiotics have been considered as a potential substitution of antibiotics to control pathogens and treat infectious diseases in aquaculture.In the present study a strain of Lactobacillus pentosus,named as L.pentosus SF-1,was isolated from waters in aquaculture.The species identification of this strain was conducted by 16S rRNA sequence,and the physiological and biochemical characteristics of this strain were assessed.Furthermore,the virulence,antibiotic sensitivity,cell surface characteristics and acid/base-resistance of L.pentosus SF-1 were determined to evaluate the probiotic potentials of this strain.Specifically,L.pentosus SF-1 is sensitive to most common antibiotics,and no hemolysin was generated from it,indicating the safety of this strain to hosts.In addition,L.pentosus SF-1 was able to tolerate the artificial gastric juice at pH 3 for 4 h and the artificial intestinal fluid at pH 6.8 or 8.0 for 6 h.Moreover,the analysis of self-aggregation and the adhesion of L.pentosus SF-1 to organic solvents suggested a high potential of L.pentosus SF-1 to inhabit the hosts,which was confirmed by testing the colonization of L.pentosus SF-1 in germ-free zebrafish.Interestingly,L.pentosus SF-1 displayed a high bactericidal activity against several bacterial pathogens.Consistently,the incubation of L.pentosus SF-1 significantly promoted the expression of antimicrobial components in zebrafish,contributing to the protection of the fish from E.tarda infection in vivo.Taken together,the probiotic strain L.pentosus SF-1 could be applied as anti-infection reagent in aquaculture.

Anti-infective immune functions of type Ⅳ interferon in grass carp(Ctenopharyngodon idella):A novel antibacterial and antiviral interferon in lower vertebrates

Type Ⅳ interferon(IFN-υ)is a recently discovered cytokine crucial for host defense against viral infections.However,the role and mechanisms of IFN-υin bacterial infections remain unexplored.This study investigated the antibacterial and antiviral functions and mechanisms of grass carp(Ctenopharyngodon idella)IFN-υ(CiIFN-υ)both in vivo and in vitro.The CiIFN-υgene was first identified and characterized in grass carp.Subsequently,the immune expression of CiIFN-υsignificantly increased following bacterial challenge,indicating its response to bacterial infections.The eukaryotic recombinant expression plasmid of CiIFN-υwas then constructed and transfected into fathead minnow(FHM)cells.Supernatants were collected and incubated with four bacterial strains,followed by plate spreading and colony counting.Results indicated that CiIFN-υexhibited more potent antibacterial activity against gram-negative bacteria compared to gram-positive bacteria and aggregated gram-negative bacteria but not gram-positive bacteria.In vivo experiments further confirmed the antibacterial function,showing high survival rates,low tissue edema and damage,reduced tissue bacterial load,and elevated proinflammatory response at the early stages of bacterial infection.In addition,the antiviral function of CiIFN-υwas confirmed through in vitro and in vivo experiments,including crystal violet staining,survival rates,tissue viral burden,and reverse transcription-quantitative real-time polymerase chain reaction(RT-qPCR).This study highlights the antibacterial function and preliminary mechanism of IFN-υ,demonstrating that IFN-υpossesses dual functions against bacterial and viral infections.

Synthesis and Characterization of a New Compound of Cobalt Ⅱ with Isonicotinamide and Evaluation of the Bactericidal Potential

In this work, the isonicotinamide was coordinated to the Cobalt ion in oxidation state +2. The relevance of this work is the investigation of the in vitro bactericidal potential of the synthesized complex when tested in Gram-positive and negative bacteria strains. This study is motivated by the need to obtain new materials that have antibiotic properties and that, in the future, may become an effective drug against resistant bacteria. A new coordination compound of Cobalt and isonicotinamide, [Co(H2O)(isn)3](BF4)2, was synthesized and described. The compound was characterized by thermoanalytical techniques TG-DTG and TG-DSC, where it was possible to propose the mechanism of thermal decomposition. Through the spectroscopy in the region of the medium infrared (FTIR), it is possible to infer the site of connection between isonicotinamide and metal. The bactericidal activity of [Co(H2O)(isn)3](BF4)2, CoCl2 and free Isonicotinamide were tested for the bacteria Streptococcus mutans (Gram+) and Escherichia coli (Gram−) and the synthesized compound showed to be sensitive for both bacteria.

Bactericidal and Photoeatalytie Activity of Fe^(3+)-TiO_2 Thin Films Prepared by the Sol-gel Method

Pure TiO2 thin films and iron doped TiO2 thin films on glass substrate were prepared by sol-gel method, and characterized by X-ray diffractometer （XRD）, thermo-gravimetric analysis （TG-DSC）, high resolution transmission electron microscope （HRTEM）, scanning electron microscope （SEM） and UV-Vis spectroscopy, respectively. The experimental results show that the pure TiO2 thin films and iron doped TiO2 thin films can destroy most of the escherichia coli and bacillus subtillis under the irradiation of 365 nm UV-light. However, the iron doped TiO2 thin film is a better photocatalyst than pure TiO2 thin film. The ultrastructural studies provide direct evidences for understanding the bactericidal mechanism of the TiO2 photocatalyst.

Bactericidal and Fungicidal Efficacy of Chlorine Dioxide in Various Workspaces

Previously, we demonstrated the virucidal efficacy of low concentration chlorine dioxide (ClO2) gas in room settings. The purpose of these studies was to evaluate novel ClO2 formats as potential biocidal interventions for real world congregate settings and air systems. Three types of studies were conducted to determine the efficacy of ClO2 in reducing bacteria and mold in various workspaces: hard and soft surfaces (gymnasium & equipment), aerosol (in-room), and within a laboratory environment. The study demonstrated that ClO2 was highly effective against both bacteria and mold with reduction ranging from 85.0% - > 99.4% for bacteria and >99.4% for yeast and mold. Treatments on hard and soft surfaces (gymnasiums and sports equipment), reduced bacteria by an average of 90% - 95%. The following treatments were applied overnight: 1) hard surface spraying with dilute ClO2 solutions, 2) carpet and tumbling treatments with powdered ClO2 releasing impregnates, and 3) HVAC treatment and overall room deodorization with low dose ClO2 gas from controlled releasing sachets. The in-room study treating air with a ClO2 filtration media also indicated significant air and surface room efficacy, with an average of 94% reduction in bacteria after 24-hour, and 99.4% reduction in mold after 24-hours. In a related air study, a biological combination of Raoultella terrigena and Staphylococcus aureus was injected as a bio-aerosol into a 4-inch diameter pipe with air flowing at approximately 1200 ft/min. Dry ClO2 gas was introduced into the air flow to achieve an effective concentration of 5 or 10 ppmv. Air samples were collected at sampling ports downstream from the fan at 10, 22, 55 and 100 ft along the pipe and used to evaluate changes in airborne bacteria and mold. Testing was conducted in a laboratory setting at ambient conditions. The data showed ClO2 gas reduced viable organisms at both gas concentrations, and indicated that reductions were higher for 10 ppmv concentration, and longer pipe runs. In a final study, laboratory application of gaseous chlorine dioxide was tested. Low gas release filter testing demonstrated significant surface reductions of airborne bacteria with an overall average 99.4% reduction in the 24-hour testing period. Higher gas treatments of a class II biological cabinet reduced bacillus spores on steel coupons throughout cabinet by 6 log. ClO2 was effective as a bactericidal and fungicidal treatment providing significant reduction in both surface and air. Novel product delivery forms may be useful for rapidly disinfecting air and solid surfaces in complex congregate settings.

TiO_2 thin film photocatalyst

It is well known that the photocatalytic activity of TiO_2 thin filmsstrongly depends on the preparing methods and post-treatment conditions, since they have a decisiveinfluence on the chemical and physical properties of TiO_2 thin films. Therefore, it is necessary toelucidate the influence of the preparation process and post-treatment conditions on thephoto-catalytic activity and surface microstructures of the films. This review deals with thepreparation of TiO_2 thin film photo-catalysts by wet-chemical methods (such as sol-gel,-reversemicellar and liquid phase deposition) and the comparison of various preparation methods as well astheir advantage and disadvantage. Furthermore, it is discussed that the advancement ofphotocatalytic activity, super-hydrophilicity and bactericidal activity of TiO_2 thin filmphotocatalyst in recent years.

Structure Elucidation and Biological Screening of Bis(4-{[(E)-(2-Hydroxybenzylidene)amino]methyl}-cyclohexane-carboxylato-O)-triaqua-cadmium

Using a bidentate ligand, a Schiff base 4-（{[（Z）-（2-hydroxyphenyl）methyldene]amino}methyl）cyclohexanecarboxylic acid, complex I（ML2, where M = Cd（Ⅱ）） was synthesized and characterized by IR spectroscopy and X-ray crystallography. It crystallizes in monoclinic system, space group C2/c, M_r = 685.04, 0.34 mm × 0.26 mm × 0.14 mm, a = 54.050（3）, b = 6.1220（3）, c = 9.5081（5） A, β = 90.229（2）°, Z = 4, C_（30） H_（40） CdN_2 O_9 and V = 3146.2（3） A^3. Complex I was screened for its bactericidal activity against four bacterial strains Chromohalobactersalexigens, Chromohalobacterisraelensis, Halomonashalofila and Halomonassalina and fungicidal activity against Aspergillusnigerand Aspergillusflavus. Antimicrobial activity results showed that the synthesized complex displayed good anti-fungal activity against two fungal strains. It was found to be inactive against four different bacterial strains analyzed and was negative for bactericidal effect.

Construction of Antibacterial Peptide CecropinB Eukaryotic Recombinant Vector and Its Expression in Dairy Goat Mammary Gland Epithelial Cells

To investigate the expression of antibacterial peptide CecropinB cDNA in dairy goat mammary gland epithelial cells,the CecropinB gene was cloned and was inserted into a eukaryotic vector pECFP-C1 to construct the recombinant plasmid pECFP-B by genetic engineering technique.Recombinant plasmid pECFP-B was transfected into dairy goat mammary gland epithelial to detect the bactericidal activity of CecropinB.The expression of CecropinB was also detected.The result of RT-PCR demonstrated CecropinB gene was expressed in transfected cells.CecropinB recombinant plasmid DNA was injected into udders and CecropinB was expressed in mammary gland,exhibiting bactericidal activity to Staphylococcus aureus in vivo experiments.

In Vitro Antimicrobial Activity Study of Some New Arginine-based Biodegradable Poly （Ester Urethane）s and Poly （Ester Urea）s

Bactericidal activity of some arginine based biodegradable polymers-PEURs （poly （ester urethane）s） and PEUs （poly （ester urea）s） with low cytotoxicity was studied in in vitro experiments. Various bacterial strains both Gram-positive and Gram-negative were used to explore the bactericidal activity of the cationic polymers. As the test objects, the following microorganisms were used： Bacillus subtilis, Staphylococcus aureus, Mycobacterium album, Pseudomonas fluorescens, Escherichia coli, Actinomyces griseus and Aspergillus niger. The obtained results showed that the new cationic polymers suppressed the growth of the studied microorganisms and the bactericidal activity of the tested cationic polymers strongly depending on their chemical structure.

Multifunctional polyeugenol-based nanoparticles with antioxidant and antibacterial properties

Over the past few decades,extensive scientific has been dedicated to polymer synthesis employing renewable resources.In this study,we devised and synthesized multifunctional polyeugenol-based nanoparticles,exhibiting remarkable antioxidant and antibacterial properties.The grafting of eugenol onto the nanoparticle surface was achieved via a thiol-ene chemical reaction with a grafting rate of 3.5%.To comprehend the properties of the synthesized nanoparticles,we employed Fourier transform infrared spectroscopy,X-ray photoelectron spectroscopy and pyrolysis-gas chromatography mass spectrometry.Subsequent scanning electron microscopic and transmission electron microscopic analyses revealed the presence of a crosslinked structure within the polyeugenol-based nanoparticles,as well as a heteroge-neous microsphere structure on the surface.Due to the inherent crosslinking structure,the polyeugenol-based nanoparticles demonstrated robust the resistance to solvents,as ascertained through thermog-ravimetric analysis and solvent resistance tests.Notably,nitrogen adsorption/desorption studies confirmed the adsorption capacity of the polyeugenol-based nanoparticles,rendering them potentially suitable for drug transport applications.Moreover,the assays for assessing cytocompatibility and reactive oxygen species scavenging activities demonstrated better performance of the eugenol-based nano-particles compared to eugenol.Furthermore,the polyeugenol-based nanoparticles exhibited certain bactericidal activities against Escherichia coli,Staphylococcus aureus,and Fusobacterium nucleatum.Consequently,these observations indicated the nontoxic nature and expansive application prospects of the polyeugenol-based nanoparticles in the domains of medicine and food preservation.This work presented a pioneering concept for the development of antioxidant and antibacterial multifunctional polymer materials derived from eugenol.

In Vitro Bactericidal Activity of Jinghua Weikang Capsule(荆花胃康胶丸)and Its Individual Herb Chenopodium Ambrosioides L.against Antibiotic-Resistant Helicobacter Pylori

Objective： To investigate the bactericidal effects of Jinghua Weikang Capsule （荆花胃康胶丸） and its major component Chenopodium ambrosioides L. on antibiotic-resistant Helicobacter pylori. Methods： Four clinical antibiotic-resistant H. pylori strains were isolated and incubated in liquid medium containing Jinghua Weikang Capsule or Chenopodium ambrosioides L. By means of time-kill curve method, the average colony counts and bactericidal rate were calculated at time points of 0, 4, 8 and 24 h after the incubation and the time-kill curves were charted. Results： Both Jinghua Weikang Capsule and Chenopodium ambrosioides L. at a concentration of 0.64 g/L showed obvious bactericidal effect against antibiotic-resistant H. pylori after 4 h of incubation. Conclusion： Jinghua Weikang Capsule and Chenopodium ambrosioides L. are considered to be active against antibiotic-resistant H. pylori in vitro.

Fabrication linalool-functionalized hollow mesoporous silica spheres nanoparticles for efficiently enhance bactericidal activity

To develop a novel food preservation technology for efficiently enhance bactericidal activity in a long term,hollow mesoporous silica spheres(HMSS)with regular nanostructures were applied to encapsulate natural organic antimicrobial agents.The chemical structures,morphologies and thermal stabilities of linalool,HMSS and linalool-functionalized hollow mesoporous silica spheres(L-HMSS)nanoparticles were evaluated by polarimeter,field emission scanning electron microscope(FE-SEM),transmission electron microscope(TEM),fourier transform infrared(FT-IR),thermal gravimetric analyzer(TGA),nitrogen adsorption-desorption,zeta potential and small angle X-ray diffraction(SXRD).The results show that the linalool was successfully introduced into the cavities of HMSS,and the inorganic host exhibited a high loading capacity of about 1500 mg/g.In addition,after 48 h of incubatio n,the minimum bactericidal concentrations(MBC)of L-HMSS against Escherichia coli(E.coli),Salmonella enterica(S.enterica)and Staphylococcus aureus(S.aureus),Listeria monocytogenes(L.monocytogenes)were decreased to be 4(<5)mg/mL and 8(<10)mg/mL,respectively.These results revealed linaloolfunctionalized hollow mesoporous spheres could efficiently improve the bactericidal activities of the organic component.Furthermore,SEM images clearly showed that L-HMSS indeed had an extremely inhibitory effect against gram-negative(E.coli)and gram-positive(S.aureus)by breaking the structure of the cell membrane.This research is of great significance in the application of linalool in nano-delivery system as well as food industry.

Stabilizing the Bactericidal Activity of Hydrogen Peroxide:A Brandnew Function of Certain Chinese Herbs

Objective： To explore natural herbs to maintain the bactericidal activity of hydrogen peroxide （H2O2）. Methods： Eighteen extracts of Chinese herbs were prepared complying with the standard protocol. Each of the solutions was then mixed with 1% H2O2. The mixtures were handled with two approaches： autoclaved daily for one, two or three times; stored at room temperature from one through five years. Then the bactericidal activity were evaluated by assaying the minimal bactericidal concentration （MBC） and minimal inhibitory concentration （MIC） against Gram positive （Staphylococcus aureus, ATCC25923） and Gram negative （Escherichia coli, ATCC12421） bacteria. Results： While mixed with 1% H2O2, 10 out of 18 kinds of assessed Chinese herbs displayed MBC values at 1：12800 or higher after three times of autoclaving, and 8 of them preserved such level of MBC value after stored at room temperature for three years. Some Chinese herbs, i.e. Fl. Scutellariae, R. Coptidis, R. Bupleuri, H. Epimedii, C. Phelledendri and F. Chrysanthemi, can significantly maintain the bactericidal activity of diluted H2O2. Conclusions： Certain Chinese herbs can effectively stabilize the bactericidal activity of H2O2 undergoing autoclave or long-term storage. This paper reported a brandnew pharmaceutical function of Chinese herbs and provided experimental data for the potential enhancement of H2O2 usage while its stability level is promoted.

Dual functional AgNPs-M13 phage composite serves as antibacterial film and sensing probe for monitoring the corrosion of chromium-containing dental alloys

The preparation of silver nanoparticles(AgNPs)with microbe or plant tissues as bio-template offers green approach,while it suffers from low harvest and purification is needed.Herein,we propose a facile protocol for one-pot preparation of AgNPs using M13 phage as bio-template by simply mixing AgN03 solution with alkali M13 phage.In the obtained AgNPs-M13 phage composite,Cr(Ⅲ)selectively coordinates with the amino residues on phage surface and leads to the aggregation of AgNPs through the bridging of M13 phages.This makes it feasible for colorimetric sensing of Cr(Ⅲ)by measuring the absorbance ratio of AgNPs at 600 and 405 nm,which provides a LOD of 14 nmol/L.The composite also showed favorable bactericidal activity for both Gram-positive and Gram-negative bacteria,making it a promising candidate as antibacterial film in chromium-containing dental alloys and meanwhile serve as a sensing probe for monitoring the corrosion of the dental alloys.

Antimicrobial activity of silver loaded MnO_2 nanomaterials with different crystal phases against Escherichia coli

Silver-loaded MnO_2 nanomaterials（Ag/MnO_2）,including Ag/α-MnO_2,Ag/β-MnO_2,Ag/γ-MnO_2and Ag/δ-MnO_2 nanorods,were prepared with hydrothermal and impregnation methods.The bactericidal activities of four types of Ag/MnO_2 nanomaterials against Escherichia coli were investigated and an inactivation mechanism involving Ag~＋ and reactive oxygen species（ROS）was also proposed.The bactericidal activities of Ag/MnO_2 depended on the MnO_2 crystal phase.Among these nanomaterials,Ag/β^-MnO_2 showed the highest bactericidal activity.There was a 6-log decrease in E.coli survival number after treatment with Ag/β^-MnO_2 for120 min.The results of 5,5-dimethyl-l-pyrroline-N-oxide spin-trapping measurements by electron spin resonance indicate OH and O_2^- formation with addition of Ag/β-MnO_2,Ag/γ-MnO_2 or Ag/δ-MnO_2.The strongest peak of OH appeared for Ag/β-MnO_2,while no OH or ·O_2^-signal was found over Ag/α-MnO_2.Through analysis of electron spin resonance（ESR） and Ag＋elution results,it could be deduced that the toxicity of Ag~＋ eluted from Ag/MnO_2 nanomaterials and ROS played the main roles during the bactericidal process.Silver showed the highest dispersion on the surface of β-MnO_2,which promoted ROS formation and the increase of bactericidal activity.Experimental results also indicated that Ag/MnO_2 induced the production of intracellular ROS and disruption of the cell wall and cell membrane.

Plant extract-loaded bacterial cellulose composite membrane for potential biomedical applications

Bacterial cellulose(BC)has been extensively explored as biomaterial for various biomedical applications owing to its non-toxic nature and unique structural morphology and impressive physicochemical and mechanical properties.However,its high production cost and lack of antimicrobial activity have restricted its large-scale production and therapeutic applications.Therefore,the current study is aimed to devise a strategy for low-cost BC production and develop its composite with bioactive materials to bless it with antimicrobial activity.Herein,5 mm thick reticulated fibrous and highly porous BC was produced by utilizing the wasted rotten tomatoes as the production medium.The produced bacterial cellulose waste(BCW)(i.e.,produced from wastes)was ex-situ modified with bioactive plant extract(PE)obtained from Euclea schimperi,and the bactericidal activity of the developed BCW/PE was evaluated against Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli through disc diffusion and colony forming unit(CFU)count methods.The BCW/PE composite showed high bactericidal activities against S.aureus and produced clear inhibition zone whereas negligible activity was observed against E.coli,indicating its bactericidal activity mainly against the Gram-positive bacterium.Overall,this study illustrates that there is a huge potential for developing valuable biomaterials from food wastes and utilizing their liquid holding capabilities for value-added applications in medical and pharmaceutical fields.

Enoxacin-loaded Poly(lactic-co-glycolic acid) Coating on Porous Magnesium Scaffold as a Drug Delivery System: Antibacterial Properties and Inhibition of Osteoclastic Bone Resorption

Implant-associated infection remains a difficult medical problem in orthopedic surgery. Therefore, the development of multifunctional bone implants for treating infection and regenerating lost bone tissue, which may be a result of infection, is important. In the present study, we report the fabrication of enoxacin- loaded poly （lactic-co-glycolic acid） （PLGA） coating on porous magnesium scaffold （Enox-PLGA-Mg） which combine the favorable properties of magnesium, the antibacterial property and the effect of inhibition of osteoclastic bone resorption of enoxacin. The drug loaded PLGA coating of Mg scaffold enables higher drug loading efficiency （52%-56%） than non-coating enoxacin loaded Mg scaffold （Enox-Mg） （4%-5%）. Enox- PLGA-Mg exhibits sustained drug release for more than 14 days, and this controlled release of enoxacin signifcantly inhibits bacterial adhesion and prevented biofilm formation by Staphylococcus epidermidis （ATCC35984） and Staphylococcus aureus （ATCC25923）. Biocompatibility tests with Balb/c mouse embryo fibroblasts （Balb/c 3T3 cells） indicate that PLGA-Mg has better biocompatibility than Mg. Finally, we also demonstrate that Enox-PLCA-Mg extract potently inhibited osteoclast formation in vitro. Therefore, Enox- PLCA-Mg has the potential to be used as a multifunctional controlled drug delivery system bone scaffolds to prevent and/or treat orthopedic peri-implant infections.